Small molecule gas storage adapter

ABSTRACT

Various embodiments are generally directed to a casing connected to a top cap structure that consists of an adapter flange extending to an adapter barrel that is configured to fit wholly within the casing. The adapter barrel can be separated from the casing by an annulus that is filled to a predetermined annulus pressure while an internal chamber defined by the adapter barrel contains a gas having a small molecular size at a storage pressure that is greater than the predetermined annulus pressure.

SUMMARY

A casing, in accordance with various embodiments, is adapted for storageof gas with small molecular size by being connected to a top capstructure that consists of an adapter flange extending to an adapterbarrel that is configured to fit wholly within the casing. The adapterbarrel is separated from the casing by an annulus that is filled to apredetermined annulus pressure while an internal chamber defined by theadapter barrel contains a gas having a small molecular size at a storagepressure that is greater than the predetermined annulus pressure.

An adapter, in other embodiments, is utilized by forming a gas tightmetal-to-metal seal by attaching a collar of a top cap structure to acasing prior to positioning an adapter barrel over the casing. Theadapter barrel is pumped into the casing until an adapter flange thatextends from the adapter barrel to contact the collar and form a sealedannulus between the adapter barrel and the casing. The annulus is filledwith a material having low compressibility before the annulus is cappedat a predetermined annulus pressure. An internal chamber of the adapterbarrel is filled with a gas having a small molecular size to a storagepressure. The internal chamber is drained and experiences a drop fromthe storage pressure and subsequently is refilled with the gas andpressurized to the storage pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents portions of an example gas storage system in whichvarious embodiments may be practiced.

FIG. 2 depicts a line representation of portions of an example gasstorage container arranged in accordance with some embodiments.

FIG. 3 conveys a line representation of gas molecules that may be storedin the gas storage system in accordance with assorted embodiments.

FIGS. 4A-4C respectively illustrate portions of an example gas storageassembly that can be utilized in accordance with various embodiments.

FIG. 5 depicts portions of an example gas storage assembly configuredand operated in accordance with some embodiments.

FIG. 6 is an example gas storage assembly installation routine that canbe executed with the various embodiments of FIGS. 1-5 .

DETAILED DESCRIPTION

Embodiments of a gas storage assembly generally utilize an adapter tosecurely seal a casing to entrap small molecule gas, such as hydrogen,helium, and neon.

The volume of gases consumed for personal, commercial, and industrialpurposes has increased over time and appears to continue to grow. Thestorage of fluids and some gases can be safely facilitated with avariety of storage materials and configurations, such as metals,ceramics, stone, and polymers. However, the storage of relatively smallgas molecules poses a difficult challenge for short-term, and long-term,time periods as leaks and/or gas permeation can occur despite thepresence of materials and seals that effectively store large moleculegases. The presence of pressure can further exacerbate the difficultiesof storing small molecule gas due to the molecular construction ofstorage tanks, containers, and seals.

With these issues in mind, an adapter constructed and utilized inaccordance with various embodiments can safely store small molecule gasin a tank/container under dynamic pressure over extended periods oftime. The use of an adapter that safely stores small molecular gassesallows a tank/container that is suitable for storing large moleculegases to store gasses of nearly any molecular size. Efficientinstallation and utilization of a tank/container adapter to store gaseswith small molecule sizes under pressure allows older generation largemolecule gas storage to be repurposed with minimal labor, time, andcost.

FIG. 1 depicts portions of an example gas storage system 100 arrangedwith a subterranean gas storage container 102 and a gas storage tank104. It is noted that a container is meant to be positioned partially,or completely, under a ground level (GL) while a tank is meant to bepositioned wholly above the ground level. As shown, the gas storagecontainer 102 is arranged to be wholly underground and continuouslyextending to a depth (D) into one or more subterranean formations.

The gas storage container 102 consists of at least one casing 106 thatis sealed on the bottom 108 by a plug 110 and on the top 112 by a capassembly 114. It is contemplated that multiple lengths of separatecasing 106 are joined together to form the gas storage container 102 andextend to the predetermined depth, such as 50 feet or more, to allow gasstorage under static, or dynamic, pressure, such as greater than 100psi. The gas storage container 102 can have one or more ports 116 thatallow piping/tubing to move gas into, and out of, the casing 106.

The gas storage tank 104 may be constructed of any type, number, andsize of materials that form a sealed volume 118 accessed by gastransmission lines 120 to allow ingress, pressurization, and egress ofvarious volumes of gas over time. Although the container 102 and tank104 are not displayed with gauges, valves, and safety relief equipment,it is contemplated that the respective components 102/104 can beconfigured with one or more gas regulating, controlling, moving,pressurizing, and/or safety equipment. It is noted that the movement,pressurization, and storage of gas in the respective components 102/104can be initiated, terminated, and controlled by one or more userspositioned on site, which can be characterized as physically presentwith the components 102/104, or off site, which can be characterized asconnected to the respective components 102/104 electronically.

FIG. 2 depicts a line representation of portions of an example gasstorage container 130 that may be used as part of a gas storage systemin combination with one or more other gas storage components. The gasstorage container 130 defines a storage volume 132 defined by theinterior, sealed aspect of the casing 106. A bottom plug 110, or bottomcap assembly 134, can establish a bottom container extent while a topcap structure 136 establishes a top container extent that provides gastransmission and pressurization.

While the materials and sealing components outlined in FIG. 2 are fullycapable of storing conventional gases as well as small molecule gases,permeation into the materials by small molecule gases, such as Hydrogen,will accelerate fatigue through embrittlement and significantly shortenthe service life of the storage. If embrittlement due to the storage ofsmall molecule gas under pressure, such as above 1,000 psi, degrades thecompetency of the container 130 to the point of catastrophic failure,the release gas from a container 130 or from one or more locations abouta container 130 can pose a serious hazard, particularly when flammablegases are being stored.

FIG. 3 displays molecular diagrams of assorted gases that can be storedin a gas storage container. An example molecule is H₂ 140, which has anatomic size and molecular configuration that is relatively smallcompared to other gases, such as methane 150 and ethane 160.Specifically, H₂ 140 has a length 142 and width 144 that defines amolecular area that is significantly smaller than the molecular area ofmethane 150, as defined by width 152 and height 154 measurements, orethane 160, as defined by width 162 and height 164 measurements. Whilenot drawn to scale, the molecules of FIG. 3 generally illustrate howstorage of H₂ 140 can be more difficult than methane 150, ethane 160, orother natural gas hydrocarbons due to the relatively small size,particularly with regard to the material porosity of many gas storagecasings, such as lead, steel, and iron.

Accordingly, various embodiments utilize an adapter to allow a typicalcasing 106, such as an oil well casing constructed of carbon steel orother steel alloys to be used to safely and reliably store gas with arelatively small molecular size, such as H₂. FIGS. 4A-4C respectivelydepict line representations of portions of an example gas storagecontainer 170 configured and operated to store small molecule gas atrelatively high pressures, such as over 1000 psi. The container utilizesa casing 106 that defines an interior volume along with a bottom plug orcap (not shown) and a top cap structure 172. The cap structure 172, insome embodiments, has a collar 174 that attaches to the casing 106 andpresents a fastening surface 176 for an adapter flange 178 and lid 180.

FIG. 4A illustrates how the cap structure 172 fits together, onceassembled, with the adapter flange 178 sandwiched between an upperportion 182 of the collar 174 and the lid 180. The enlarged size of theupper portion 182 allows one or more fasteners 184 to extend through thecap structure 174 to form a gas tight assembly that is accessed via oneor more ports 116. The exploded view of FIG. 4B illustrates how theadapter flange 178 is connected to an adapter barrel 186 that defines aninternal volume that is less than the volume of the outer casing 106. Itis contemplated that the adapter barrel has a solid bottom that forms awater tight and air tight receptacle without installation of a plug,cap, lid, or cover onto the bottom of the barrel 186, opposite theflange 178.

While not limiting, various embodiments construct the adapter flange 178and barrel 186 of forged, cast, machined, or assembled material, such asaluminum, which exhibits low permeability to small molecules, such as H₂and high resistance to embrittlement, which extends the life of theadapter. It is contemplated that some, or all, of the adapter 178/186can be coated with one or more materials to lower gas permeability evenmore and/or increase rigidity, corrosion resistance, and fatigueresistance. Some embodiments coat different aluminum adapters with apolymer, rubber, ceramic, or graphene material to allow a casing 106 toemploy an uncoated adapter or one of various adapters that exhibitdifferent operational characteristics due to the respective coatings.

The adapter 178/186 is configured for installation into a casing 106without adjusting or removing the casing 106 from its position, whetherpartially or completely underground. It is contemplated that the adapter178/186 can be utilized in above ground gas storage tanks. The size andshape of the adapter barrel 186 relative to the casing 106 produces anannulus 188 of empty space extending between the casing 106 and barrel186 along the entirety of the barrel sidewalls 190. That is, an annulus188 can be measured as the distance from an interior sidewall 192 of thecasing 106 to a barrel sidewall 190. The annulus 188 allows the adapterbarrel 186 to be installed, and removed, from the casing 106 withoutdamaging the adapter barrel 186 and provides space for a dampingmaterial to be placed between the casing 106 and barrel 186.

In the close-up line representation of the annulus 188 in FIG. 4C, thethreads 194 of the casing 106 are shown, which interact with matchingthreads of the collar 174 to mate a casing sealing surface 194 with thecollar 174 via a metal-to-metal connection. In other words, the casing106 is configured with threads 194 that flow into a tapered surface 196that defines a sealing surface 196 that is brought into contact with thecollar 174 to form a gas tight seal. While one or more sealing materialscan be introduced between the collar 174 and casing 106, assortedembodiments machine the collar 174 and casing sealing surface 194 totolerances that provide a gas and/or fluid tight seal strictly with ametal-to-metal connection.

FIG. 5 depicts a cross-sectional line representation of portions of anexample gas storage container 210 arranged in accordance with variousembodiments. The container 210 employs a casing 106 with first threads194 positioned to secure a bottom cap 212 to a first region while secondthreads 194 secure a top cap 214 to a second region. It is noted thatsome embodiments utilize one or more plugs to seal a bottom of thecasing 106 while other embodiments employ matching cap structures212/214 that thread a collar onto the casing 106 and secure a lid ontothe collar via fasteners, as illustrated in FIGS. 4A-4C.

Although the cap structures 212/214 may having matching configurations,the cap structure 212/214 located at the top portion of the casing 106secures the adapter flange 178 between the collar 174 and lid 180 toensure the adapter 178/186 does not inadvertently move or get ejectedfrom the casing 106. The secure position of the adapter 178/186 definesthe annulus 188. While the annulus 188 may be kept empty, or in a vacuumpressure differential, the cyclic filling and removing of gas within theadapter internal volume 216 can cause at least the adapter barrel 186 toexpand and contract. Such barrel 186 movement can cause fatigue to thebarrel 186 material as well as damage to the sidewalls of the casing 106and/or barrel 186. Hence, some embodiments fill the annulus 188 withdamping that reduces the expansion and contraction of the barrel 186material in response to pressurization and depressurization of theinternal volume 216.

The annulus 188, in various embodiments, is filled with a propyleneglycol and brought to a constant pressure, such as 10 psi. Althoughother materials, and combinations of materials, can be used to fill theannulus 188, propylene glycol has an extremely low freezing point, lowcompressibility, and is compatible with corrosion inhibitors while beingenvironmentally friendly. As the annulus 188 represents a finite andrelatively uncompressible volume of glycol, pressure exerted on thebarrel 186 is transferred to the outer casing 106 with minimal expansionof the barrel 186. As a result, fatigue and physical damage to thebarrel 186 due to expansion and contraction of cyclic pressurizationsare managed to meet, or exceed, the rate of deterioration due toembrittlement over time. The adapter and lid 180, in some embodiments,are sacrificial and are replaced according to a predetermined schedulethat maintains a margin of safety for the container and extends theservice life of the outer casing 106 and cap assemblies indefinitely.

While the adapter barrel 186 fits inside the casing 106, the vacuumpressure of the annulus 188 and bottom of the casing 106 can makeremoval difficult. To accommodate a more efficient removal, the annulus188 is plumbed to one or more fill ports 218 that can be positioned in abottom cap structure 172, as shown, or other locations that provideaccess to the annulus 188 from outside the casing 106. It is noted thatpositioning the fill port 218 at the bottom-most extent of the annulus188, casing 106, and container 210 allows the annulus to be efficientlyfilled and drained with liquid, as opposed to a side positioned portthat would potentially not drain some annulus liquid without highpressure. The annulus fill port 218 is connected to at least one feedline 220 that allows for the ingress, egress, and pressurization of thegas/fluid with respect to the annulus 188.

The annulus fill port 218 can be complemented by one or more annulusmonitor port 222 that may be positioned anywhere on the casing 106, butin some embodiments extends through a top collar 174, as shown in FIG. 5. A bleed line 224 allows pressure, gas, and/or fluid to be releasedupon selection of a valve 226. The bleed line 224 further allows one ormore gauges 228 to monitor conditions of the annulus 188, such aspressure, humidity, and temperature. Use of one or more ports 218/222that access the annulus 188 allows the adapter 178/186 to behydraulically pumped into position within the casing 106, whichalleviates difficulties associated with purely mechanical, or pneumatic,adapter 178/186 installation.

For instance, incompressible fluid can be pumped into, and out of, theannulus 188 to draw the adapter 178/186 into, or out of, the casing 106.As a result, the annulus 188 can be used to aid adapter 178/186installation and removal, which allows for different adapters 178/186 tobe utilized for a container 210 over time to accommodate different gasstorage conditions and capabilities. The monitoring of one or moreannulus ports 218/222 provides data that can be used to determine thereal-time current annulus gas/fluid condition. That is, pressure, andother environmental conditions in the annulus 188, can be tracked overtime to calculate at least the volume, compressibility, density, andrelative pressure of the gas/fluid in the annulus 188. Such annulus 188conditions can be used to schedule proactive and/or reactive maintenancethat serves to maintain the annulus 188 so that charging and dischargingof gas in the adapter internal volume 216 does not induce more thanminimal fatigue, corrosion, and mechanical war on the adapter 178/186.

Some embodiments utilize only metal-to-metal seals to create a gas, orfluid, tight enclosure with the container 210, as conveyed in FIG. 4Cand shown by the casing/collar interactions 230 of FIG. 5 . Otherembodiments can complement metal-to-metal seals of the casing/collarwith one or more metal or non-metal gaskets 232, such as cork, rubber,polymer, ceramic, and synthetic materials capable of sealing at workingpressures. The use of one or more gaskets 232 in a cap structure 172 canbe changed over time and allow the container 210 to provide optimalsmall molecule gas storage over a diverse range of temperatures andpressures.

FIG. 6 conveys a flowchart of an example adapter utilization routine 240that can be executed with assorted embodiments of FIGS. 1-5 to providegas storage for gases that have relatively small molecular size. Thepresence of a hollow, unfilled casing allows step 242 to begin theprocess of installing a single small molecule adapter into the casing.It is contemplated that the casing is constructed of a material, such assteel alloy, iron, or lead, that is not conducive to small molecule gasstorage due to susceptibility to embrittlement. As such, the adapter canbe constructed of a dissimilar material than the casing, such asaluminum, ceramics, and nanocomposites, that provides superiorresistance to embrittlement than the casing.

Once the storage volume is depressurized and the lid 180 of the capassembly is removed, the adapter is positioned over the hollow casing instep 242. Insertion of the adapter begins in step 244 and can involveusing suction on the annular fill line 220 to pull the adapter into thecasing until an adapter flange 178 contacts a cap structure collar 174,as illustrated in FIGS. 4A & 5 . Once the adapter flange 178 is seatedon the structure collar 174, the lid 180 is secured in place, whichseals both the annulus 188 and the interior volume 216 of the adapterwhile isolating the annulus 188 from the interior volume 216.

The metal-to-metal seal may be complemented by one or more gaskets 232positioned between the adapter flange, collar, and lid, The gas tightseal 230 and the gasket 232 between the collar 174 and the adapterflange 178 seal the annulus 188. The gasket 232 between the lid 180 andthe adapter flange 178 seals the small molecule gas within the volume ofthe adapter 216 at pressures over 1000 psi.

With the annulus formed after the top cap structure has been assembledand secured so that the adapter flange is locked in place along with theadapter barrel, the volume of the annulus is displaced in step 248 bypumping a fluid or gas with low compressibility, such as propyleneglycol down the annular fill line 220 and venting the volume of theannulus out the annular bleed valve 226. Once displaced, the bleed valve226 is closed and the annulus is pressurized to a predetermined relativepressure, such as 10 psi, and the annulus drain/fill port is closed instep 250 and the annulus has a static condition until the adapter barrelexpands and contracts to induce force and/or pressure on the annulus. Itis noted that while the annulus drain/fill port remains closed duringgas storage operations within the adapter barrel, the annulus monitorport can remain open to one or more gauges or be selectively opened withvalving to allow at least annulus pressure to be detected.

Next, step 252 cyclically fills the internal chamber of the container,as defined by the adapter barrel, to a predetermined pressure and volumeof gas before depressurizing the internal chamber as pressurized gas isreleased from the container. It is contemplated that the internalchamber is pressurized to a common pressure cyclically in step 252 ordynamic pressures are utilized over time depending on environmentalconditions and/or desired amount of gas to be stored. Step 252 may beconducted for any amount of time with any number of gas fills/drainsbeing conducted and associated with the internal chamber of the adapterbarrel being pressurized and depressurized.

At any time, a user/operator of the container can evaluate in decision254 to alter the annulus. If an annulus modification is in order, suchas in response to a change in pressure of the annulus or a desire for adifferent compressibility value for the annulus, step 256 opens theannulus drain/fill port 220 and displaces the volume of the annulus outthe bleed valve, which replaces the damping material of the annulus andrepressurizing the annulus to different operating conditions. Someembodiments of step 256 simply fill and/or repressurize the annuluswithout displacing the annulus with new damping material/fluid. At theconclusion of the modification(s) to the annulus in step 256, theannulus is capped by returning to step 250.

In the event no annulus alteration is necessary from decision 254, theroutine 240 returns to step 252 and the cyclical use of the internalchamber of the adapter barrel for the storage, and dispensing, of gas ata predetermined pressure, such as above 1000 psi. Through the use of themonitored and controlled annulus, along with the resistance toembrittlement of the adapter barrel compared to the outer casing, gascan be reliably stored and dispensed over time without material fatigue,corrosion, and leakage. The ability to interchange adapter barrelswithout modifying or moving an outer casing extends the service life ofthe container and allows for efficient alteration of the gas storagecapabilities and performance of a gas storage container with minimalequipment and manpower.

What is claimed is:
 1. A method comprising: attaching a collar of a topcap structure to a casing; positioning an adapter barrel within thecasing; placing an adapter flange extending from the adapter barrel intocontact with the collar to form a sealed annulus between the adapterbarrel and the casing; filling the annulus with a non-hardening liquidhaving low compressibility to support the adapter barrel within thecasing and to facilitate subsequent removal of the adapter barrel fromthe casing; capping the annulus at a predetermined annulus pressure;filling an internal chamber with a gas having a small molecular size toa storage pressure, the internal chamber defined by the adapter barrel,the liquid in the annulus compressed between the adapter barrel and thecasing to support the adapter barrel responsive to the storage pressureof the gas.
 2. The method of claim 1, wherein the predetermined annuluspressure is altered by selecting at least one valve connected to theannulus, but not the internal chamber of the adapter barrel, the valveconfigured to subsequently flow a portion of the liquid from the annulusafter removal of the gas from the internal chamber defined by theadapter barrel.
 3. The method of claim 1, wherein the storage pressureremains for more than a week without adding pressure to the internalchamber.
 4. The method of claim 1, wherein the gas having a smallmolecular size is hydrogen.
 5. The method of claim 1, wherein the gashaving a small molecular size is methane.
 6. The method of claim 1,wherein the casing and adapter barrel are constructed of differentmaterials.
 7. The method of claim 1, wherein the adapter barrel ispumped into the casing using the non-compressible liquid in the annulus.8. The method of claim 1, wherein the adapter barrel is subsequentlyremoved from the casing without moving or altering the casing byincreasing a pressure supplied to the liquid in the annulus.
 9. Themethod of claim 1, wherein the collar is threaded onto the casing toform a gas tight seal.
 10. The method of claim 1, further comprising abottom cap structure that sealingly closes a bottom portion of thecasing, wherein the annulus continuously extends between the adapterbarrel, the casing and the bottom cap structure.
 11. The method of claim1, wherein the non-hardening liquid is propylene glycol.
 12. The methodof claim 1, wherein a non-metal sealing member forms a gas tight sealbetween the adapter flange and the collar.
 13. The method of claim 1,further comprising a drain port coupled to the annulus configured tosubsequently facilitate flowing removal of the liquid from the annulus.14. The method of claim 1, wherein the casing extends under a groundlevel into a subterranean formation.
 15. A method comprising: attachinga collar to an outer casing; placing an annular barrel into the outercasing to form an annulus between an outer sidewall surface of theannular barrel and an inner sidewall surface of the outer casing; usingan adapter flange to sealingly attach the collar to the annular barrel;filling the annulus with propylene glycol in a liquid form; filling aninterior storage space of the annular barrel with compressed hydrogen,the propylene glycol transferring an expansion force generated by thecompressed hydrogen from the outer sidewall surface of the annularbarrel to the inner sidewall surface of the outer casing; andsubsequently using a pump to induce a flow of the propylene glycolwithin the annulus.
 16. The method of claim 15, further comprising usinga non-metal sealing member between the adapter flange and the collar toseal the interior storage space.
 17. The method of claim 15, wherein theplacing step comprises pumping the annular barrel into the outer casingusing the propylene glycol.
 18. The method of claim 15, wherein aninterior sidewall surface of the adapter flange is coated with a lowpermeability material to facilitate retention of the hydrogen within theinterior storage space.
 19. The method of claim 15, wherein thesubsequently pumping step comprises increasing a pressure of thepropylene glycol using the pump to eject the adapter barrel from thecasing.
 20. The method of claim 19, using a first drain port to remove aquantity of the hydrogen from the interior storage space, and using asecond drain port to remove a quantity of the propylene glycol from theannulus.